Device for separating fluid mixtures

ABSTRACT

The invention relates to a device for separating fluid mixtures, in particular for separating water from oil, comprising a vacuum container ( 10 ) with several sub-chambers ( 26, 44, 40 ). According to the invention, at least one liquid constituent of the fluid mixture can be transported from the vacuum container after separation, by means of a transport device ( 12 ) and the other constituents can be extracted from the vacuum container ( 10 ) in the form of gas and/or steam, using a vacuum pump ( 20 ). One of the sub-chambers ( 26 ) of the vacuum container ( 10 ) houses a heating device ( 28, 30 ), which heats the fluid mixture, the latter being guided into an additional sub-chamber ( 40 ) and being separated into its constituents by traversing a packed bed. The invention therefore allows even cold and consequently viscous fluid mixtures to be supplied, by means of the heating device, for separation inside the aforementioned vacuum container.

[0001] The invention relates to a device for separating fluid mixtures,in particular for separating water from oil, comprising a vacuum tankwith several sub-chambers, and at least one liquid component of thefluid mixture can be transported out of the vacuum tank after separationby a delivery means and the corresponding other components can beextracted from the vacuum tank in gas and/or vapor form by means of avacuum pump.

[0002] In a non-generic device for separating an oil/water mixture asclaimed in EP 0 148 444 A2 there is a pre-separation space in whichfirst the coarser components of the oil are separated from the mixture.The mixture which has been precleaned in this way is then delivered to acoalescence chamber which contains a plurality of coalescing bodieswhich consist of an oleophilic plastic and are lighter than water.Extremely fine oil particles also settle on the oleophilic, specificallylarge surface of these body, flow together on the bodies and rise aslarger, easily separable oil droplets into the separation space wherethey can collect and can be removed in the oil collection space. Thewater flows out of the separation space by way of a partition throughanother pipe. The known device is large and although oil separation ismaintenance-free with the device over a longer time interval, theoleophilic coalescence bodies from time to time must be replaced by newones; this leads to downtimes of the system. With respect to the size ofthe system, the discharge performance on the oil and water which havebeen separated from one another is relatively low. Especially under coldambient conditions and for moreover cold fluid mixtures to be separatedthe water removal performance, especially the rate with which waterremoval takes place, is insufficient.

[0003] EP 0 733 389 B1 discloses a generic device for separating fluidmixtures, especially of oil and water, with a vacuum tank in which thisfluid mixture can be atomized by means of an atomization means, and atleast one liquid component of the fluid mixture after its separation canbe drained from the vacuum tank and the corresponding other componentscan be suctioned in gas and/or vapor form out of the vacuum tank bymeans of the vacuum pump. The known atomization means has an atomizernozzle for the fluid mixture, and the liquid components can be drainedby mean of a hydraulic pump which can be driven by a hydraulic motor,which form a structural unit located within the vacuum tank. Theindicated hydraulic motor can be driven by the fluid mixture which canbe set into motion by another drive as soon as a definable fill level inthe vacuum tank requires discharge of the component which is liquid atthe time by means of the hydraulic pump. Based on the atomization meansit is possible to achieve almost optimum separation of the componentswith a small structural size of the device, separation also beingeconomically favorable with respect to energy input. But it has beenfound that especially in applications at low and very low temperaturesthe atomization means is fault-susceptible and is not especially wellsuited.

[0004] Based on the above described prior art, the object of theinvention is to improve a device for separating fluid mixtures, inparticular for separating oil and water, with a low structural size,while retaining the advantages, which allows optimum separation of thecomponents and can be operated economically favorably, in such a waythat it can also be used at low and very low temperatures. The pertinentobject is achieved by a device with the features of claim 1.

[0005] In that, as specified in the characterizing portion of claim 1,one of the sub-chambers of the vacuum tank holds a heating means whichis used to heat the fluid mixture which, routed to another sub-chamberas it flows through the packed bed, undergoes separation into itscomponents, it is possible to deliver cold and consequently viscousfluid mixtures by means of the heating means to separation within theindicated vacuum tank. Thus the separation device as claimed in theinvention also becomes of interest for use in construction machinery andmilitary vehicles, where outside of maintenance installations with thecorresponding building equipment, therefore also in the field, servicingof the hydraulic fluid can be undertaken by the water being separatedfrom the oil. Another application consists also in separation of waterfrom gasoline or water from kerosene, for example in aircraft.

[0006] The heating means, preferably in the form of an electricallyoperated heating means, can be regulated in terms of its heating outputand can also be tailored so that in a wide range of temperatures of thefluid mixture it can be handled appropriately in terms of separationwithin the separation device. Integration of the heating means into onesub-chamber of the vacuum tank results in that only a small portion ofthe heat is released to the vicinity; this leads to improved efficiencyand also improves the rate of water removal.

[0007] In one preferred embodiment of the device as claimed in theinvention, one sub-chamber with the integrated heating means extendsalong the entire vacuum tank, the other sub-chamber with the packed bedencompassing the first sub-chamber, and another third sub-chambercoaxially to the second sub-chamber and in the lengthwise direction ofthe vacuum tank likewise following the latter encompassing the firstsub-chamber. Division into different sub-chambers within the vacuum tankensures that the heating means can occupy a large amount of space withinthe vacuum tank; this is advantageous in that the fluid mixture can thenbe routed over a very long section along the heating means. Acorrespondingly long residence time in the second sub-chamber is ensuredby way of the other sub-chamber with the packed bed then, so that alonger time interval is available for the separation or gas removalprocess. Rapid drainage of the separated liquid portions from the vacuumtank to the outside is then possible by way of the other thirdsub-chamber with the packed bed.

[0008] In another preferred embodiment of the device as claimed in theinvention, in a fourth sub-chamber which extends parallel to the firstsub-chamber within the entire vacuum tank there is a level monitoringmeans which provides information about the fill level of the vacuum tankrelative to the respective liquid component. Preferably it is providedhere that the level monitoring means triggers a first delivery meanssuch that when a given fill level boundary is not reached within thevacuum tank, the liquid component leaving the tank is passed onto thefirst sub-chamber with the heating means. Regardless of the fill levelof the separation device and especially of the vacuum tank it isconsequently possible to conduct a continuing separation process whichis especially independent of how much fluid mixture to be separated isbeing supplied from the outside to the separation device. In addition tothis more or less continuous operation which proceeds moreover favorablyin terms of energy input, the fluid mixture which has already beenseparated can again be supplied to the actual separation device again inorder to improve the separation results in further separation process.In this respect it is then ensured that fluid from which the air andwater have been almost completely removed leaves the separation devicefor its further application.

[0009] In another preferred embodiment of the device as claimed in theinvention, another delivery means by way of a filter unit withdraws thefluid mixture from a withdrawal point, the first delivery means by wayof a switching means delivering the liquid component to the withdrawalpoint, alternatively to delivery to the heating means. If the levelmonitoring means shows that the fill level within the vacuum tank andespecially in its fourth sub-chamber is too high, a switching valve isactuated accordingly and by way of the first delivery means, especiallyin the form of a motor-hydraulic pump unit, the liquid component ispassed directly onto the withdrawal point from which in turn theseparation device removes the fluid mixture by the second deliverymeans. The respective withdrawal point which is shared can be formed forexample by the fluid tank of a construction machine or a militaryvehicle, such as a tank or armored personnel carrier.

[0010] In another preferred embodiment of the device as claimed in theinvention, the vacuum pump with its suction force adjoins the top of thevacuum tank, in the opposite direction of the fluid mixture flow takingplace from top to bottom through the second sub-chamber with the packedbed. The arrangement of the vacuum pump which is the top arrangement inthis respect and also the countercurrent principle within the vacuumtank ensure a high separation rate and moreover streamlining within thevacuum tank for the medium which is flowing at the time is achieved.

[0011] In another preferred embodiment of the device as claimed in theinvention, the vacuum tank can be connected to an air supply, andpreferably by way of a filter unit and an adjustable choke. In this waythen purified air in definable amounts can be supplied to the vacuumtank in order to be able to set and specify the respective negativepressure in the vacuum tank in this way. Preferably it is furthermoreprovided that the fluid-carrying connection to the heating means and theparts of the fluid lines in the delivery means which are each suppliedby a hydraulic pump discharge into a common connecting piece. In thisway the free path and use of pipework can be reduced.

[0012] If the device is assembled with all its components to be mobilein a transport unit, the separation device can be used on site so thatin a military application a military vehicle can also be repaired andmaintained in the open field.

[0013] The separation device as claimed in the invention is detailedbelow using one embodiment as shown in the drawings. The figures areschematic and not to scale.

[0014]FIG. 1 shows the basic connection diagram of the separationdevice;

[0015]FIG. 2 shows the separation device which implements the connectionas shown in FIG. 1 as a mobile transport unit.

[0016] The device for separating fluid mixtures, especially water fromoil, has a vacuum tank 10 into which the fluid mixture, here in the formof an oil/water mixture, can be delivered. The liquid component of thefluid mixture, here in the form of oil or another hydraulic medium,after completed separation can be transported out of the vacuum tank 10by a delivery means which is designated as a whole as 12. The deliverymeans 12 which is the first one in this case has a hydraulic pump 16which can be driven by an electric motor 14. For the respective removalthe first delivery means 12 is connected by way of a pipeline 18 tocarry fluid on the bottom of the vacuum tank 10. Furthermore, theseparation device has a vacuum pump 20 which is conventional forapplications in this respect and which is connected by way of aconnecting line 22 which is shown only partially in FIG. 2 in the upperpart of the vacuum tank 10 to the latter, carrying fluid. The output 24of the vacuum pump 20 can be connected to a receiving tank which is notdetailed or to another liquid drain line (neither is shown). If thevacuum pump 20 must release air to the vicinity, there can be acorresponding release device which is not detailed. In any event, watervapor in the form of a gas and/or in the form of steam can be safetyreleased from the vacuum tank 10 by means of the vacuum pump 20. As canbe seen from FIG. 2, the conveyor means 12 of the separation device islocated as a unit underneath the vacuum tank 10. As a modular componentthe vacuum pump 20 is in turn a component of the separation device, inthe direction of looking at FIG. 2 seen from the right and above thisdelivery means 12 and likewise outside of the vacuum tank 12.

[0017] As is to be seen from FIG. 2, the vacuum tank 10 is divided intoseveral sub-chambers. The first sub-chamber 26 extends off-center alongthe entire vacuum tank 10 and is made in the manner of a hollowcylinder. Within this first sub-chamber 26 as part of a heating means 28there is an electrically heatable heating rod 30. The heating rod 30which likewise has a cylindrical outside profile, fits into the firstsub-chamber 26 while maintaining a radial distance, the distanceestablished in this way being used for fluid transport of the fluidmixture which is still to be separated. The transport direction of thefluid mixture within the first sub-chamber 26 is indicated with thecorresponding arrows. The heating rod 30 itself viewed in the directionof looking at FIG. 2 with its top end is held by the sealing plate 32 ofthe vacuum tank 10, the heating rod 30 as part of a heating means beingprovided with an electrical supply 34.

[0018] Fundamentally the heating rod 30 of the heating means 28 works inthe manner of electrical resistance heating, as is known from immersionheaters or the like. The cylindrical first sub-chamber 26 on the otherhand viewed in the direction of looking at FIG. 2 with its bottom endrests on a lower end plate 36 which seals the vacuum tank 10 to thebottom. Conversely, on its other end the first sub-chamber 26 with itsoutside wall has a distance to the upper sealing plate 32 so that thefluid mixture can leave the first sub-chamber 26 by way of theseparating gap 38 which has been formed in this way, in order to bereleased to the second additional sub-chamber 40. The respective secondsub-chamber 40 is located coaxially to the first sub-chamber 26 andencompasses it with its cylindrical outside wall. In this way, withinthe second sub-chamber 40 a receiving space 42 is formed which is usedto hold a packed bed which is not detailed. The packed bed in thisrespect can consist for example of special steel material with aplurality of individual filaments or the like in order to increase thesurface for the fluid mixture which is to be separated in this way inthe manner of a shower bed. Furthermore, the residence time of the fluidmixture which is to be separated in the second sub-chamber 40 isincreased by the packed bed so that with respect to this longerresidence time, more and more time is available for the actualseparation process.

[0019] By integrating the heating means 28 into the vacuum tank 10 andespecially into the first sub-chamber 26 only a small portion of theamount of heat is released to the vicinity, so that improved efficiencyand an improved rate of water removal are achieved. By heating the fluidmixture, better separation of the water/oil mixture by way of the vacuumpump 20 is possible, which pump otherwise discharges with the free endof its connecting line 22 into the vacuum tank 10, and directly into thesecond sub-chamber 40 with the packed bed. If the fluid mixture whichhas been delivered to the first sub-chamber 26 is highly supercooled,there is also the possibility of heating the fluid mixture which is tobe separated accordingly; this benefits the separation process.Furthermore, it is also possible to treat unusually viscous fluid, asoccurs at low temperatures, by way of the separating device.

[0020] In the fluid direction downstream and moreover underneath thesecond sub-chamber 40 there is a third sub-chamber 44 which is separatedby way of a type of separating or perforated sheet 46 from the secondsub-chamber 40. In this way the packed bed which is not detailed can besupported on the top of the separating or perforated sheet 46 andremoval of the liquid components of the fluid mixture from which waterhas been removed to the third sub-chamber 44 is ensured by way of thepertinent separating means 46. The third sub-chamber 44 in turnencompasses likewise in a coaxial arrangement the first sub-chamber 26and otherwise terminates in terms of its outside diameter flush with theoutside diameter of the second sub-chamber 40. The already addressedpipeline 18 which is connected to the first delivery means 12accordingly fits into the third sub-chamber 44, carrying fluid with itsother end. The second and third sub-chamber 40 and 44 extend jointlyalong the entire vacuum tank 10 and first end flush with the sealingplate 32 and then with the end plate 36. On the bottom end of the thirdsub-chamber 44 it however has an opening 48 which produces afluid-carrying connection to the other fourth sub-chamber 50.

[0021] Depending on the overall fill level situation within the vacuumtank 10, in the fourth sub-chamber 50 a corresponding fluid levelarises, a level monitoring means designated as a whole as 52 whichmonitors and adjusts the pertinent fill level. For this purpose thelevel monitoring means by way of an electrical terminal located on thetop of the sealing plate 32 is connected to a control means which isdesignated 56 as a whole and which also has the corresponding controlpanel inputs and an emergency off function 58.

[0022] The indicated level monitoring means 52 within the fourthsub-chamber 50 has a lengthwise rod 60 along which a float-buoyancy bodyis movably located, depending on the respective fill level within thefourth sub-chamber 50, which allows a conclusion about the overall filllevel situation within the vacuum tank 10 regarding fluid. Thefloat-buoyancy body can move between a minimum position 62 and a maximumposition 66. The respective fluid level moves between these positions 62and 66 and furthermore there is an emergency off float 64 available forsafety purposes. The limit switches (not shown) which are monitored byway of the control means 56 provide for the first delivery means 12 tobe triggered upon reaching the lower limit switch and consequently at alow fill level within the vacuum tank 10 such that the liquid componentleaving the vacuum tank 10 by way of the third sub-chamber 44 is passeddirectly onto the first sub-chamber 26 with the heating means 28. Forthis reason the control means 56 controls a 3/2-way switching valve 68which in its actuated position clears the fluid-carrying path betweenthe pipeline 18 and the hydraulic pump 16 to a connecting line 70 whichdischarges exclusively into the fluid-carrying area of the firstsub-chamber 26 by way of the lower end plate 36.

[0023] When the float-buoyancy body reaches the top limit switch, thelevel monitoring means 52 by way of the control means 56 triggers the3/2-way switching valve such that it retains its unactuated positionshown in FIG. 1, in which the pipeline 18 is connected by way of thehydraulic pump 16 to a drain line 72, as shown, which discharges withits free end by way of an hand-actuated check valve 74 into a withdrawalpoint, for example in the form of a tank T. In the pertinent operatingposition it can be ensured that the vacuum tank 10 with its sub-chamberscannot be overfilled, but that reliable drainage in the direction of thetank T is possible. Consequently, it is possible by way of the levelmonitoring means 52 and the control means 56 to exactly adjust the filland working state, with undersupply of the vacuum tank 10 the liquidfluid which has already been separated in the sense of an internalclosed return flow being routed back to the first sub-chamber 26 withthe heating means 28.

[0024] In order to be able to ensure the supply of the vacuum tank 10with the fluid mixture which is to be separated at all, the separationdevice furthermore has a second delivery means 76 which in turn has ahydraulic pump 80 which can be driven by means of an electric motor 78.The indicated motors 14 and 78 can of course also consist of ordinaryhydraulic motors. The hydraulic pump 80 by way of a withdrawal line 82and a coarse filter 84 and by way of another hand-actuated shut-offmeans 86 removes fluid from the withdrawal point in the form of the tankT and passes the water-containing fluid mixture which is thus conveyedon to a filter unit 88 which by way of a spring-loaded nonreturn valve90 ensures that fluid cannot flow back to the filter unit 88unintentionally in the opposite direction out of the connecting line 70and by way of the delivery line 92. Otherwise this would be possible forexample if the hydraulic pump 80 were not to build up a sufficient fluidpressure. By way of the pertinent second transport or delivery means 76the supply of the vacuum tank 10, especially the supply of the firstsub-chamber 26 with the heating means 28 from the withdrawal point (tankT), is ensured. The withdrawal site or tank T itself can in turn besupplied continuously, but also discontinuously with the fluid mixturewhich is to be separated from the machine side.

[0025] To prevent negative pressure from developing in the vacuum tank10 such that the operation of the entire device could be at risk,provision is made such that the vacuum tank 10 be connected to an airfeed 94 which has an air filter 96 and an adjustable choke 98. The airfeed into the vacuum tank 10 can be dictated by way of the latter choke98. Furthermore, by way of the air filter 96 it is ensured thatcontaminated air could not penetrate into the vacuum tank 10 and couldadversely affect the separation process there. The fluid-carryingconnection 70 to the heating means 28, 30 and parts of the fluid lines92 of the delivery means 12, 76 which are each supplied by the hydraulicpump 16, 80 discharge into a common connecting piece 100 which allowssupply of the vacuum tank 10 first by way of the external supply fromthe tank T and then by way of the inner circulation depending on thefill level within the vacuum tank 10. As follows furthermore from FIG.2, all the aforementioned components of the device are combined to bemobile in a transport unit 102, in this case transport on a factoryfloor, road or the like being possible by means of a set 104 of wheels,for example, in the form of four individual wheels. Rail or air cushionoperation would also be conceivable.

[0026] In addition to the indicated removal of water from the oil/watermixture, the device can also be used for comparable fluid mixtures, forexample to remove aqueous condensates from aviation fuel (kerosene) inthe tanks of aircraft.

[0027] In addition to the indicated automatic operation of the waterremoval system, it is moreover possible to monitor the pressuresituation in the vacuum tank 10 by way of a connected pressure gauge 106(compare FIG. 1); this also aids safety. Within the vacuum tank 10preferably a working temperature from roughly 20° C. to roughly 60° C.,depending on the application, is used and an absolute pressure of 22,000Pa (200 mbar) is set; this corresponds to a negative pressure of 80,000Pa (0.8 bar). Overall the device is set such that a working point in thevicinity of the vapor pressure curve of water develops which ispreferably slightly above the vapor pressure curve. A working pointslightly above the vapor pressure curve can be easily technicallyachieved and in terms of energy is within acceptable limits. In the areaof this working point or working range the water vapor then separatesfrom the oil-water mist in the area of the fluidized bed and can bediverted by way of the intake area by means of the vacuum pump 20 out ofthe vacuum tank 10. The oil mist itself settles on the bottom of thefluidized bed and moreover in the area of the separating or perforatedsheet 46 at latest as liquid and visibly fills the third sub-chamber 44and moreover also the fourth sub-chamber 50 of the level monitoringmeans 52.

[0028] In the indicated separation process, in addition to removingwater from oil, removal of gas from it is also achieved, the gaseslikewise collecting in the intake area of the vacuum pump 20 and in thisway being removed at the same time from the vacuum tank 10. The feedline of the fluid mixture which is to be separated to the heating rod 30of the heating means 28 in the vacuum tank 10 acts like a heat exchangerand preheats the inflowing fluid mixture. This likewise benefits theefficiency and water removal rate of the device as claimed in theinvention, since only a limited amount of heat per area can betransferred to the fluid mixture without damage occurring. Integratingthe heating in the housing parts of the vacuum tank 10 moreover resultsin a space-saving and weight-reducing construction.

[0029] For better understanding, the entire device is now explained inconclusion using its manner of operation. The hydraulic pump 80 intakesthe fluid mixture (oil/water mixture) to be separated from the tank Tfrom which water is to be removed and fills the vacuum tank 10 by way ofa filter 88 and the chamber with the heating rod 30. Moreover filtrationand heating of the fluid mixture take place if the heating means 28 hasbeen started by the control means 56. Based on the temperature and theset negative pressure, then water is removed from the oil in the vacuumtank 10. At the same time oil is delivered by way of the hydraulic pump16 from the vacuum tank 10 and is supplied depending on the level switchsignal of the level monitoring means 52 to the vacuum tank 10 or thetank T from which water is to be removed. If malfunctions occur,especially due to the vacuum tank 10 no longer being filled, the levelmonitoring means 52 especially by way of a switch located right at thebottom in the vacuum tank 10 can ascertain the pertinent completeemptying situation for the tank 10 and then undertake emergencyshutdown, for example, by the control means 56 turning off the indicatedhydraulic pumps 16, 80. As already described, humid air is intaken fromthe vacuum tank 10 by way of the vacuum pump and at the same time theroom air which has been filtered by way of a so-called gas ballast choke98 can be allowed to flow back into the vacuum tank 10 by way of theinterface 94 and the filter unit 96. As a result of the pressure drop inthe vacuum tank 10 the room air is then released and the water vaporpartial pressure drops so that water can be removed from the oil.

1. A device for separating fluid mixtures, in particular for separatingwater from oil, comprising a vacuum tank (10) with several sub-chambers(26, 44, 40), and at least one liquid component of the fluid mixture canbe transported out of the vacuum tank (10) after separation by adelivery means (12) and the corresponding other components can beextracted from the vacuum tank (10) in gas and/or vapor form by means ofa vacuum pump (20), characterized in that one of the sub-chambers (26)of the vacuum tank (10) holds a heating means (28, 30) which is used toheat the fluid mixture which, routed to another sub-chamber (40) as itflows through the packed bed, undergoes separation into its components.2. The device as claimed in claim 1, wherein one sub-chamber (26) withthe integrated heating means (28) extends essentially along the entirevacuum tank (10), wherein the other sub-chamber (40) with the packed bedencompasses the first sub-chamber (26) and wherein another thirdsub-chamber (44) coaxially to the second sub-chamber (40) and in thelengthwise direction of the vacuum tank (10) likewise following thelatter encompasses the first sub-chamber (26).
 3. The device as claimedin claim 2, wherein in a fourth sub-chamber (50) which extends parallelto the first sub-chamber (26) within the entire vacuum tank (10) thereis a level monitoring means (52) which provides information about thefill level of the vacuum tank (10) relative to the component which isliquid and which is to be drained.
 4. The device as claimed in claim 3,wherein the level monitoring means (52) triggers a first delivery means(12) such that when a given fill level boundary is not reached withinthe vacuum tank (10), the liquid component leaving the tank (10) ispassed onto the first sub-chamber (26) with the heating means (28). 5.The device as claimed in claim 4, wherein another delivery means (76) byway of a filter unit (88) withdraws the fluid mixture from a withdrawalpoint (tank T) and wherein the first delivery means (12) by way of aswitching means (68) delivers the liquid component to the withdrawalpoint (T), alternatively to delivery to the heating means (28).
 6. Thedevice as claimed in one of claims 1 to 5, wherein the vacuum pump (20)with its suction force adjoins the top (32) of the vacuum tank (10) andwherein, in the opposite direction of the fluid mixture, flow takingplace from top to bottom through the second sub-chamber (40) with thepacked bed.
 7. The device as claimed in one of claims 1 to 6, whereinthe vacuum tank (10) can be connected to the air supply (94), andpreferably by way of an air filter unit (96) and an adjustable choke(98).
 8. The device as claimed in one of claims 5 to 7, wherein thefluid-carrying connection (70) to the heating means (28) and the partsof the fluid line (18, 92) of the delivery means (12, 76) which are eachsupplied by a hydraulic pump (16, 80) discharge into a common connectingpiece (100).
 9. The device as claimed in one of claims 1 to 8, whereinthe heating means (28) is electrically operated.
 10. The device asclaimed in one of claims 1 to 9, wherein all its components are combinedto be mobile in a transport unit (102).